Method for forming an expanded-resin container about a body

ABSTRACT

A body to be packaged is suspended on filaments in an upwardly open porous mold which is lined with a gas-pervious sheet material. The mold is capped and a synthetic resin is introduced therein and expanded, the air in the mold being displaced out through the mold walls, to completely encapsulate the body. The supporting filaments, extending from the package so formed can be drawn across each other to cut an opening in the package permitting the packaged body to be removed. The sheet material covers the outside of the package, being integral therewith, and protects the package while permitting it to be written on.

FIELD OF THE INVENTION

The present invention relates to an expanded-resin body usable as ashipping container. More specifically this invention concerns a methodof and apparatus for forming such a container about a body to bepackaged.

BACKGROUND OF THE INVENTION

There is an increasing trend toward the use of expanded synthetic resinsfor manufacturing miscellaneous bodies such as packages, structures andwall elements, containers, or various receptacles. Most of these bodieshave an irregular outer surface which cannot be written on or otherwisecarry legible inscriptions concerning the product enclosed therein, itsdestination, or its manufacturer. At the same time such containers areso soft that the handling incident to shipping often scratches them upso badly that they are quite unattractive, if they have not opened bythemselves.

Packages consisting essentially of shells or halfcasings of expandedsynthetic resin, e.g. foamed urethane, are already known and widelyused. Due to their poor mechanical strength these shells or half-casingsare not used as widely as could be desired. Each shell or the like maycontain several objects in different respective cavities or cutouts, butcan only be used for packing objects having a well-defined shape. Ifthis shape is modified a new package must be prepared. This limitsconsiderably the use of such packages since a great many different typesmust be kept on hand and they must also be shipped in their own cartonsso that they may be marked and so that the soft foam will not be ruined.

A known packing method consists in utilizing polyurethane as a fillerbetween the objects to be protected and a fluid-tight ease. The objectsare enclosed in a fluid-tight envelope from which the air is removed asmuch as possible by an expensive vacuum pump. Then the bagged object isplaced in the case on blocks or wedges, the interior of the case beinglined with some kind of sheet material acting as a mold-release agent.The reagent mixture is then introduced slowly into the case in order tofill it completely and prevent the formation of air pockets or bubbles.A lid is then nailed in place and the entire mass is allowed to cure.

Although such a package is generally considered to be very good, it hascertain disadvantages. The blocks or wedges supporting the object on thebottom of the case transmit shocks due to handling directly to theobject. In addition opening of such a package is quite difficult sincechunks of the packaging foam must be cut away, which is quite dangerousthe closer the unpackager gets to the object.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved package and a method of and an apparatus for making same.

Another object is the provision of such a package which is easy to open.

Yet another object is to provide a packaging method which can be usedwith a variety of different objects having different shapes.

A further object is to provide a package which can be written on andwhich resists surface scratching.

SUMMARY OF THE INVENTION

The package according to the present invention comprises a hollow foamedsynthetic-resin mass completely surrounding the body and covered with anenvelope which is bonded to it and permits the package to be markedwhile protecting it from scratching or other damage. A plurality offilaments or thread-like elements are imbedded in the mass and extendunder the object packed so that they can be pulled up and serve to cutthe object free of its packaging, while they can also serve for pickingup of the packaged object by means of a crane or the like.

With this arrangement as the expanded resin polymerizes, the thread-likeelements serve to support the object but they do not transmit to theobjects shocks and stresses.

The mold for carrying out this method comprises an open-top box orvessel having perforated side walls and a lid, also perforated, adaptedto be detachably locked thereon and formed with at least one aperture.

According to another feature of the invention, each one of the openingsformed through its cover is associated with a pouring duct consisting ofa tubular section of flexible, elastic material provided at one end withan annular rib adapted to co-act with the outer face of the cover forlocking said duct to this cover and adjacent thereto with a resilientradial skirt adapted to clamp against the inner surface of the cover theedge of the cutout formed in the porous envelope under the coveropening. The other end of said tubular section is adapted, after fillingof the mold with the reaction mixture, to be sealed by pinching so thatthis tubular duct constitutes an expansion regulating chamber.

Thus, when the reaction mixture has been poured into the mold, theflexible pouring duct is closed and sealed by pinching its free outerend and then constitutes an elastic expansion chamber adapted to preventany undesired and detrimental overpressure from developing within themold either in case of faulty metering of the mixture or from excessiveheating of the mold or product such that the expansion is increased. Aplurality of pouring ducts of this character may be disposed at spacedintervals in certain areas of the mold for constituting a plurality ofexpansion chambers and avoiding local overpressures.

DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will becomeapparent from the following description, reference being made to theaccompanying drawing in which:

FIGS. 1 and 2 are sectional views illustrating two steps of the methodof manufacturing a first embodiment of the packing;

FIG. 3 is a view from above showing the means for suspending the objectin the packing illustrated in FIGS. 1 and 2;

FIGS. 4 and 5 are perspective views of the complete packing, at thebeginning and during the operation, respectively;

FIGS. 6 and 7 are fragmentary vertical sections showing in enlargedscale a modified embodiment of the pouring duct associated with the moldof FIGS. 1 and 2;

FIG. 8 is a perspective and exploded view of a leg according to anotherembodiment of the present invention;

FIG. 9 is a side and cross-sectional view showing the leg of FIG. 8,incorporated in the packing;

FIG. 10 is a perspective view partly in section showing the otherembodiment of the packing; and

FIG. 11 is a perspective view of the packing of FIG. 10.

SPECIFIC DESCRIPTION

To manufacture the packing of this invention a porous mold 1, forexample of perforated sheet-metal, is used. Its inner walls are rigidand lined with a porous sheet 2 consisting, for example, of burlap for apurpose explained below. When the mold has concave or convex surfaces,this cloth 2 is made to conform to the mold's contours. The mold, havingthe general configuration of an open-top box, is associated with a coveror lid 6 and comprises wall elements either hinged together or simplydetachable from one another for mold-stripping purposes.

It may be noted that if the mold shape is developable it is possible touse a cloth 2 of relatively simple shape, for example rectangular.

When the mold has thus been lined, a number of thread-like orfilamentary elements 3 are disposed therein. The free ends 3a of theseelements 3 project from the mold, as illustrated in FIGS. 1 and 2, andare fastened temporarily, for example by means of clamps 7 carried bythe mold 1. These elements may consist of belts, string, threads orwires extending longitudinally and/or transversely to the mold, andpossibly interconnected by means of intermediate elements 3b, as shownin FIG. 3.

Under these conditions, the object 4 to be packed, wrapped beforehand ina synthetic-resin envelope not liable to adhere to the expanded resin tobe subsequently poured into the mold, is rested (suspended) on theportions of thread-like elements 3 which lie within the mold, asillustrated in FIG. 1. Spacers or distance-pieces 5 may be disposedabove the object 4 and between the taut portions of the filaments 3.

The mold 1 is then closed by applying the cover or lid 6 thereto, thiscover 6 being also perforated and having its inner face lined with aporous sheet 8 tensioned on it by means of hooks 9 disposed along itsperiphery. This cover 6 is formed with an opening 10 which, in thisembodiment, is associated with a tubular duct 11 also rigid with saidcover. The porous sheet 8 is formed with an opening registering with thecover opening 10 and having its edge clamped against the edge of thecover opening by a ring 12 of flexible and elastic material. This ring12 is formed with a central opening 13 constituting the pouring orifice.Moreover, it constitutes the seat of a detachable plug 14 adapted to fitinto the tubular duct 11 and formed with means for interlocking thisplug and duct, such as radially projecting studs 15 co-acting withcorresponding retaining notches 16 of said duct, as in a bayonetmounting.

When the cover 6 is fitted to the mold 1 and locked thereto for exampleby means of releasable fasteners 17 illustrated diagrammatically inFIGS. 1 and 2, the reaction mixture is poured through the orifice 13 ofring 12. Upon completion of this one-shot molding operation the plug 14is fitted in position and locked to prevent any escape of resin 18during its expansion, this resin completely surrounding the object 4 tobe packed.

It will be noted that the air contained in the mold, together with thegas released as a consequence of the expansion of resin 18, can escapevery easily through the porous sheet 2 and the mold perforations, sothat a particularly low pressure or substantially zero inner pressure isproduced inside the mold. In any case, this pressure is not elevatedenough to damage the object 4 to be packed. Under these conditions, itis possible to employ quickexpanding reaction mixture compositions.Moreover, during its expansion the resin will conform to the contour ofthe object to be packed so that this object is encapsulated by thehollow body and the resin becomes bonded to the sheet 2 without flowingtherethrough, so that under no circumstances can this envelope beembedded in the resin. As a consequence of the low expansion pressurethe resin causes the porous envelope to form a boss at each perforationof the mold walls, the boss assisting in improving the strength of thepacking and also its adherence to the surfaces likely to support same.

Upon completion of the polymerization, the mold is opened anddismantled, and the packing thus formed is removed or stripped. Theresin mass is thus integral with the porous envelope which can receiveany inscription permitting identification of the contents, itsdestination, or the manufacturer of the packing, and at the same timeefficiently protects the relatively soft resin constituting the packing.

From the foregoing it is clear that the function of the porous sheet 2is to reinforce the expanded synthetic resin, to permit the escape ofair and gas therefrom during the molding operation and to prevent anyundesired contact between the expanded resin and the mold. It may bepointed out that the porosity of this cloth must be determined so thatit can efficiently permit the escape of gas and air during the moldingoperation while preventing the escape of the expanding resin. Moreover,the mold must also have a porosity sufficient to avoid any interferencewith the gaseous outflow, for this interference would add itself to theretarding action exerted by the porous envelope. In fact, if the foamwere retained unduly by the air pressure prevailing in the mold it mightcomplete its polymerization before it has filled the mold completely, acondition requiring the use either of overfilling material or of areaction mixture producing a higher pressure, at the expense of theobject to be packed which might not withstand this excessive pressure.

It will be seen that in the packing thus obtained the thread-likeelements 3 constantly support the object 4 resting thereon, and thatthese elements 3 can also be used for suspending or gripping the packingproper by means of their ends 3a projecting from the packing. Thisarrangement is advantageous in that it avoids the transmission of anyundesired shocks to the packed object and, more particularly, theintegral transmission to this object of the shocks received by thepacking during the handling and transport thereof.

FIG. 4 illustrates the packing 19 after completion, mold-stripping andturning upside down. The expanded resin constitutes a hollow bodyenclosing the object completely, so that only the outer sections 3a ofthe thread-like elements 3 project therefrom to permit its opening. Infact, by pulling the ends 3a of these thread-like elements 3 upwardly,as shown by the arrow 20 of FIG. 4, these elements will cut the hollowbody along the dotted lines shown in this Figure, so as to cut freepieces of the material which, after removal, permit the packed object 4to be removed.

Preferably, this operation is facilitated by cutting score lines on theouter surface of the porous envelope and also by proper instructionsprinted thereon. It will be seen that when the tearing strength of theporous envelope is such that the latter cannot be cut by means of thethread-like elements 3, this envelope must be cut by using a suitabletool before cutting the packing proper by means of said elements 3.

In the foregoing it is mentioned that the porous envelope consisted ofburlap or jute cloth, but it will readily occur to those skilled in theart that any other suitable textile sheet material, woven or not, oreven a rigid partition or wall material having a natural porosity orrendered porous throughout or on its surface, may be used. Moreover,although polyurethane constitutes the preferred expansion resin, anyother suitable synthetic resin may also be used, provided that it yieldsa low-pressure, quick-polymerizing and expanding foam material.

The packing according to this invention is particularly economical, forit requires only cheap materials easily available everywhere.Polyurethane, the most expensive among the materials constituting thispacking, is of particularly low cost in a quality perfectly suited forthis application. Its compressive strength (without deformation) isabout 300 kg. per sq. deciter (42.67 psi), corresponding to a density ofabout 20 kg. per cu.m. (0.246 lbs. per cu. ft.). Jute cloth, having acost varying considerably with its quality, has an amply sufficientresistance. The cost of the thread-like elements constitutes but a verylow percentage of the total cost of this packing. These elements mayconsist for instance of vegetable or synthetic fibres, or under specialcircumstances of mild steel in the form of binding wire when arelatively heavy object has to be supported. The distancepiecesconsisting for instance of wood are cheap elements and may even bedispensed with when the objects to be packed are relatively light inweight. The cost of the synthetic envelope wrapping the objects ispractically negligible.

Moreover, this packing is attended by several advantageous features.Thus, the fact that it can be transported by using the thread-likeelements is particularly important for with the packed object bearing onthese elements it is possible to provide a very light protection,irrespective of the load contemplated. In addition the same techniqueand in most instances the same mold may be used for various purposessince the packing is not limited from the dimensional point of view.Thus, with this packing it is possible to protect for example anaircraft jet engine as well as a precision clock, the only differencelying in the choice of basic materials. Furthermore, it is an easymatter to render the package and its content floatable. Very specialpackings, such as those either intended for jettisoning miscellaneousproducts and articles or those exposed to severe shocks, may be obtainedvery easily since polyurethanes having a wide range of very diversifiedproperties are available in the trade. If it is desired to protectrelatively small articles in a common package, the thread-like elementsmay constitute a net without appreciably increasing the cost of thepacking. In contrast to known polyurethane packings the packing of thisinvention can be opened in a particularly safe and quick manner. Afterthe removal of the object or objects contained therein, this packing canbe destroyed completely by burning, except under specific circumstancesor when the delivery of goods in fireproof or self-extinguishingmaterials is required by official regulations. Finally, from the pointof view of safety, the risk of injuring an operator during the handlingor the opening of this packing is definitely precluded.

The mold 1, whose porosity permits the escape of any air trapped thereinduring the pouring operation to avoid the formation of cavities in thehollow body thus produced, is utilized in combination with a pouringduct designated in general by the reference number 21 in FIGS. 6 and 7of the drawings. This duct comprises essentially a tubular element 22 offlexible and elastic material and having an annular rib 23 formed on itsouter wall adjacent to its lower end and an elastic radial flange 24 atthis end. As illustrated in FIG. 6, this duct projects somewhat with itsfree end through the opening 10 formed in the mold cover 6 until itsouter annular rib 23 lies just outside this cover and its flange 24bears against the under surface of the edge of the cutting formed in theporous sheet 8 associated with said cover, as already explained in theforegoing. Thus, due to the pressure created by the expandingpolyurethane poured into the mold, this flange 24 is pressed with forceagainst the inner surface of cover 6 and holds in proper position theporous sheet 8. Upon completion of this pouring operation, the upper endof the tubular duct 22 is sealed by using a clamp or pliers 25, as shownin FIG. 7. The pouring duct 21 thus constitutes an expansion regulatingchamber capable of preventing overpressures from developing inside themold, notably in case of faulty metering of the polyurethane mixture orwhen the temperature of this mixture and/or of the mold is such that theexpansion is increased unduly.

It should be pointed out that fitting the pouring duct 21 is easier thanfitting the ring 12 described hereinabove with reference to FIGS. 1 and2. Of course, the inherent elasticity of this pouring duct 21 isdeterminative of the maximum pressure to be obtained in the mold. Afterthe expanded resin has polymerized, the duct 21 is cut flush to thecover 6, just above the annular rib 23, to permit the stripping of theresulting article. If necessary, and notably to avoid localoverpressures, ducts similar to this duct 21 may be engaged throughrespective openings formed at other points in the cover 6 forconstituting supplementary expansion pressure regulating chambers.

When this manufacturing method is carried out for making packings ofrelatively heavy and cumbersome or bulky objects, the mold 1 comprisesin its lower walll openings permitting the passage of legs having oneportion embedded in the expanded resin. A typical form of embodiment ofthese legs is illustrated in FIGS. 8-11. In this example, each leg 26 isof substantially U-shaped cross section with substantially verticalwings rigid with outwardly bent legs or lips 27 extending along at leastone fraction of their length and each formed with vertical pressed lugs28. Each ledge 27 comprises at one end an upstanding flap 29 having asubstantially central orifice 30 formed therethrough. Each leg 26 isused in conjunction with a complementary reinforcing member or top plate31 having a V-shaped cross section. This reinforcing member 3b compriseson either side substantially horizontal extensions 32 formed at theirouter ends with substantially vertical walls or lips 33 adapted to actas anchoring elements. Each horizontal extension 32 has perforations 34aligned, when the reinforcing member is fitted on top of thecorresponding leg 26, with the projecting lugs 28 of the underlyingledge 27. Finally, in its portion constituting the apex of the V, eachreinforcing member 31 comprises vertical projections 35 for a purposeexplained hereinafter.

Each leg 26 engages an aperture formed in the bottom wall of the mold,near the corners thereof, before the porous envelope 8 is fittedthereto. After fitting the envelope 8 to the bottom of mold 1, thereinforcing member 31 is fitted in turn, as shown in FIG. 9. Then, theprojecting lugs 28 of leg 26 which facilitated the positioning of saidreinforcing member 31 are upset against the edges of the perforations 34through which they had been engaged. If it is contemplated to reinforcethe bottom of this packing by means of a longitudinal member 36, thelatter is advantageously disposed between two legs. In this case, asillustrated in FIG. 9, the longitudinal member 36 is perfectlypositioned by the vertical projections 35 of reinforcing member 31.

With this arrangement, when pouring the resin composition 18, the latterflows between the longitudinal member 36 and the component elements ofthe leg in order to interconnect them.

After the stripping operation and as shown in FIGS. 10 and 11, the flaps29 may be fastened to the aforesaid longitudinal member 36 for exampleby driving nails through their perforations 30.

As shown in FIG. 11, these legs 26 are disposed at a relative spacingsufficient to permit the passage of the forks 37 of a fork-lift truckwhile permitting a proper positioning of the slings 38 for lifting thepacking.

Finally, as shown in FIG. 10, the hollow body enclosing the object to bepacked may be reinforced by the provision of the above describedlongitudinal members 36 as well as up-rights 42 and cross-members 43embedded in the expanded resin. Similarly, especially in the case ofparticularly heavy and bulky packings, the longitudinal members 36 andcross-members 43 constituting the upper frame of a structure adaptedefficiently to reinforce the hollow body be further reinforced by anexternal belt element 44 of any suitable type.

Although the foregoing describes a method of manufacture according tothis invention with specific reference to the application of this methodto the manufacture of packings, it will readily occur to thoseconversant with the art that this method may also be used formanufacturing any other structure or body of expanded resin, whetherhollow or solid, and notably for manufacturing structural elements orwall or partition elements miscellaneous receptacles, containers, oreven seat elements.

I claim:
 1. A method of packaging an object for transport or storagecomprising the steps of:providing a mold cavity having perforated wallsand of a volume larger than that of an object to be packaged and ofdimensions greater than the corresponding dimensions of said object; anda cover for said cavity having perforated walls and a pouring duct;lining said walls with gas pervious sheets; suspending said object insaid cavity in all-around spaced relationship with said lined walls andupon a plurality of filaments extending from said object out of saidcavity; and closing said lined mold cavity with said lined cover andintroducing through said duct a foamable and curable polyurethanereaction mixture into the space around said object and between saidobject and said line closed mold cavity walls; causing said mixture toexpand in said space to completely fill the latter and displace air fromsaid space out of said cavity through said gas pervious sheets andperforated walls without penetration of the mixture through said sheets;and curing said mixture to form a polyurethane sheath completelysurrounding said body and covered and bonded to said sheets whileretaining said filaments embedded in said sheath.
 2. The method definedin claim 1 wherein reinforcing elements are disposed in said cavity andspaced from said body for retainment in said sheath.